691875497557 has 2 divisors, whose sum is σ = 691875497558. Its totient is φ = 691875497556.

The previous prime is 691875497483. The next prime is 691875497597. The reversal of 691875497557 is 755794578196.

691875497557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 391586841361 + 300288656196 = 625769^2 + 547986^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691875497557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 691875497557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691875497597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345937748778 + 345937748779.

It is an arithmetic number, because the mean of its divisors is an integer number (345937748779).

Almost surely, 2^691875497557 is an apocalyptic number.

It is an amenable number.

691875497557 is a deficient number, since it is larger than the sum of its proper divisors (1).

691875497557 is an equidigital number, since it uses as much as digits as its factorization.

691875497557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 666792000, while the sum is 73.

The spelling of 691875497557 in words is "six hundred ninety-one billion, eight hundred seventy-five million, four hundred ninety-seven thousand, five hundred fifty-seven".